JP2001052724A - Fuel cell battery having layered product of flat cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a cost in manufacturing a fuel cell battery. SOLUTION: In a fuel cell battery 1 having a layered product 2 of flat cells 3, 4 with a PEN (positive electrode) as an electrochemical active plate 3 and an inter-connector 4 alternately disposed, the inter-connector 4 having profiling structured so that two kinds of fluid 11, 12 flow while always making contact with the PEN is formed on one layer, a direction converting region 24 to reverse the flow direction of second fluid 12 is provided, and a cell dimension is determined so that an undesirable value of thermal stress is not exceeded in the PEN when it is actuated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fuel cell having a stack of planar cells and its use.

[0002]

2. Description of the Related Art A fuel cell which is symmetrical about its center is known from EP-A-0473540. The interconnect of this fuel cell is constructed as a special temperature-balancing body. Such an equilibrium body is a heat exchanger, whereby the supplied air is used to convert PEN (Positive Electrode), a solid electrolyte (Solid Electrolyte), a cathode (Negative), which is an electrochemically active element of the fuel cell. reaction) is transferred to the air before contacting the air. This heat exchanger is a plate-shaped hollow body, and heat is transferred to air in the internal space. The two outer surfaces of the interconnect are profiled, which allows PEN
While the electrical contact to the electrodes occurs, a gap-like electrode space is formed between the interconnector and the electrodes of the reaction components (air, fuel gas).

[0003] When a battery operates, a temperature gradient occurs in the PEN in the radial direction. This gradient is relatively small and thermal stress does not damage the sensitive solid electrolyte of PEN, especially cracks or the like.

[0004]

However, an interconnector configured as a heat exchanger is expensive, and has a very large weight in the production cost of a fuel cell. Some proposals have already been made for the manufacture of interconnectors for the purpose of cost reduction. By way of example, EP-A-0 936 688 describes an interconnector configured as a heat exchanger. In its manufacture, one or two sintered bodies are used,
This sintered body is preformed by compacting the powder mixture into the shape of the finished part and then sintering.

[0005] In view of the above problems, it is an object of the present invention to provide a fuel cell cell which can further reduce the manufacturing cost.

[0006]

The above object can be solved by the present invention.

That is, the fuel cell having the planar cell stack according to the present invention has the following features. a) PEN as an electrochemically active plate and interconnectors are alternately arranged.

B) The PEN and the interconnect have a first edge and a second edge, respectively, and the first edge and the second edge
A straight or curved region having a substantially constant width extends between the edge and the edge of the line.

C) This area is divided into small sections, and the two edges are connected through the small sections. d) The profiling of the interconnect allows the two fluids to flow separately through the cell.

E) Each sub-compartment has an entry point for a first fluid at a first edge, an entry point for a second fluid at a second edge, and an entry point for both fluids. An outflow point is provided.

F) The outlet point opens into the entire common passage. g) A second fluid is provided as a heat carrier medium for the heat of reaction released in the PEN during operation.

(H) In accordance with the present invention, the interconnector is formed in one layer and its profiling is each configured such that both fluids always flow in contact with PEN. (I) A direction change area for reversing the flow direction of the second fluid is provided at the first edge.

(J) Furthermore, the dimensions of the cell are such that during operation, the value of the undesired thermal stress in the PEN is not exceeded. The present invention is based on the recognition relating to the following considerations. The result is EP-A-0473.
Model calculations shown in No. 540 showed that the heat of reaction released in the PEN was primarily transferred to the interconnect by thermal radiation. The transport of heat by heat conduction through the electrode space filled with air can be virtually neglected. The interconnect wall has at each point a temperature that differs by only a few Kelvin from the temperature of the corresponding point on the PEN. That is, this temperature does not largely depend on the temperature of the air to be heated in the space.
The reason for this is that the heat flow between the wall and the air is relatively small.

It is not clear from the disclosed results of the model calculations that these conditions exist in the heat transport in the interconnect. If such conditions can be noticed, European Patent Publication No. EP-A-0473
It is possible to question whether an interconnector constructed as a hollow body by the method described in US Pat. No. 540 is actually necessary to remove the heat of reaction. The answer that this can be done in different ways is given by the solution according to the invention. By having the air (second fluid) already in contact with the PEN at the point of entry, the interconnect is configured as a more economical single layer rather than as a two-layer hollow body (two walls, one space). It is possible. The air that needs to be heated creates a further temperature gradient in the PEN. Such a gradient along the tangential direction (azimuthal direction) has a magnitude comparable to the radial temperature gradient that occurs in known cells. Therefore, it is expected that the thermal stress will not be substantially large in the use of the single-layer interconnector. It is also possible to provide means by which further elements of this temperature gradient can be kept relatively low.

[0015] Although the prior art described above relates to a fuel cell cell that is symmetric about a center, the solution according to the invention is, for example, in one aspect where the fuel gas (first fluid) is opposite to the fuel gas (first fluid). It is also possible to apply to a battery including a rectangular cell to which air (second fluid) is supplied on the side surface. Furthermore, if any gas composition having a combustible component is used as the first fluid and the second gas is a gas containing oxygen, it is assumed that these gases provide an exothermic reaction to supply current. Can be performed in PEN.

The fuel cell cell interconnector according to the present invention provides the following further advantages by being constructed in one layer. That is, a) the mass of the battery is smaller than the mass of a known battery, and b) the structural size is also smaller. Thus, the battery according to the invention can easily be used in mobile applications, for example, as an element for supplying current in emergency power aggregates, which can be quickly transported to vehicles or places of use.

Dependent claims 2 to 9 relate to advantageous embodiments of the invention, the subject of claim 10 being the use in mobile applications. Thus, the fuel cell according to claim 2 is characterized in that the individual interconnectors are preformed and sintered elements or are manufactured therefrom.

[0018] A fuel cell according to claim 3 is characterized in that the profiling of the interconnector has a knob-like ridge providing an electrical contact to the PEN. The fuel cell according to claim 4, wherein the profiling of the interconnector for flowing the fluid has comb-like ridges, especially on the second fluid side, and the ridges are PEN.
And providing an electrical contact to the device.

The fuel cell according to the fifth aspect is characterized in that at least a part of the comb-shaped ridge has a helical shape or is formed in a straight line and is directed in a radial direction.

[0020] In the fuel cell according to claim 6, a passage is provided in each of the small sections toward the turning area, and a cross section of the passage extends along a direction perpendicular to the PEN with a corresponding depth of the remaining profiling. It is characterized by having a greater depth in comparison.

[0021] The fuel cell according to claim 7, wherein the cell is dimensioned such that at the time of operation of the cell, at least 1/3 of the waste heat generated in the PEN reaction is emitted from the cell stack by radiation. It is characterized by.

In the fuel cell according to the eighth aspect, the cells are configured so as to be at least substantially symmetrical with respect to the center, and the first fluid can be supplied through a central passage extending in the axial direction. Yes, preferably a reformer for treating the first fluid is arranged in this passage, the common passage being provided as an outer burner chamber at the outlet point, so that the stack around the cell stack is permeable. With this configuration, the emitted reaction heat is absorbed when the second fluid flows into the cell.

The fuel cell according to the ninth aspect is characterized in that the small sections have the same size and the number thereof is 4 to 10. The invention according to claim 10 is characterized in that the fuel cell cell according to the invention is used in mobile applications, for example, as a current supply element in a motor vehicle or an emergency power aggregate.

[0024]

1 to 8 show an embodiment of the present invention.
This will be described in detail below. The fuel cell cell 1 shown schematically in FIG. 1 comprises a stack 2 of planar cells each consisting of a PEN 3 and an interconnector 4 (shown in plan view). The PENs 3 and the interconnectors 4 are arranged alternately. The PEN 3 and the interconnector 4 have a first edge 21 and a second edge 22, respectively. A region 20 extends between the rim 21 and the rim 22. Although the region 20 is shown as being linear in this figure, a curved configuration is also possible. The region 20 has a substantially constant width, and a side line 23a connecting the two edges 21 and 22.
And 23b. The interconnector 4 has profiling as shown in FIG. 2, whereby the two fluids 11 and 12 flow separately through the cell. Each subsection has an inflow point 211 for the first fluid 11 at a first edge, an inflow point 212 for a second fluid at a second edge, and an outflow point 213 for both fluids. Is provided. The outlet point 213 opens into a common passage 5 used as an afterburner chamber, which extends along the stack 2 and burns the components still present and reactive in the first fluid. Second
Of fluid 12 is provided as a heat carrier medium for the heat of reaction released on PEN3.

According to the present invention, the interconnector 4 is formed in one layer. Each of the profiling of the interconnector 4 is such that both fluids 11 and 12
It is configured to flow in contact with EN3. A turning area 24 is provided at the first edge 211, whereby the direction of flow of the second fluid 12 is reversed. Battery 1 is dimensioned such that thermal stresses in PEN 3 during operation do not exceed undesired values. The dimensions are related to the thickness of the interconnect 4, its profiling, and its width (= the width of the region 30). The air factor (the factor that specifies the stoichiometric excess of air) also plays a role in this dimensioning and in the amount of heat released by the laminate 2 to the surroundings as radiation 6.

In the periphery, a sleeve 10 is disposed at or around the cell stack 2. Since the cell stack 2 has transparency, the radiant heat 6 can be absorbed by the fluid when the second fluid 12 flows into the cell stack 2. Advantageously, a significant proportion (at least about one third) of the heat generated in the PEN reaction is carried away from the cell stack 2 by the radiation 6. That is, since the second fluid 12 can flow into the cell stack 2 at a relatively high temperature, further thermal stress generated in the PEN 3 due to direct contact with the fluid 12 is relatively small. By arranging the reformer on the first edge 21 side, the fuel is advantageously converted by the endothermic reaction into a form suitable for the PEN reaction. Thus, radiation 6 can be used as a heat source for this endothermic reaction. The single-layer interconnect 4 is preferably a preformed and sintered component or is formed from such a material. Since the materials used for the production contain chromium, the sintered parts must also be provided with a suitable protective layer.

The interconnector 4 shown in FIG. 2 has a profiling for forming a relief-like structure on a partition wall 40. These profilings have knob-like bumps 41
And a comb-shaped bump 42. These bumps 41 and 4
2 provides an electrical contact to PEN 3 while comb-like bumps 4
2 causes the fluids 11 and 12 to flow, especially on the side of the second fluid 12 flowing as a flow 12a from the rim 22 (FIG. 1), to a turning area 24 (arrow 12 '') and to flow in the opposite direction as a flow 12b It has the function of pointing to

The fuel cell 1 is advantageously configured to be symmetric about the center. FIG. 3 shows a portion of the area 20 corresponding to the small section 23. In this configuration, the rim 21 is located on the surface of the central passage, through which the first fluid 11 can be supplied into the cell stack 2. An elongate and cylindrical reformer is advantageously arranged in this passage.

FIG. 4 shows the interconnector 4 having profiling viewed from the air side. The air flow of the second fluid 12 is indicated by arrows. The comb ridges 42 have a helical shape (the subsections according to FIGS. 1 to 4 have a corresponding helical shape, not shown, but there are six subsections). Second fluid 12 (arrow 1
2 ') is the turning area 24 (arrow 12a) from the inflow point 212 through the passage 43 formed by the comb-shaped ridge 42.
Flows to In the turning area 24, the direction of the flow of the second fluid is reversed (arrow 12 ") and the fluid 12 flows in the opposite direction to the edge 22 (arrow 12b).
In the area between the passages 43 flowing in the opposite direction, the profiling consists of knob-like ridges 41, shown partially schematically as areas with crosses 41 '. At the outflow point 213, the fluid 12 flows into the passage-like afterburner chamber 5.

The passage 43 may be formed by a straight line instead of a spiral shape, and is directed radially toward the center of the interconnector 4. The profiling of the interconnector 4 can have fewer or more, preferably 4 to 10, subsections 23 instead of 6 subsections 23.

FIG. 5 shows the back surface of the single-layer interconnector 4 of FIG. In this aspect, the first fluid 11
Flows from the central passage (within the margin 211) between the knob-like ridges 41 'and by the comb-like ridges 42 to the outflow point 213 of the outer margin 212.

FIG. 6 illustrates the interconnector 4 of FIGS.
FIG. 6 is a sectional view taken along the line VI-VI in FIG. 4. The heat transport in cells 3 and 4 is indicated by arrows in the plane of the figure. The cross section of the passage 43 has a greater depth in a direction perpendicular to the PEN 3 compared to the remaining profiling depth. Due to the relatively large cross-sectional area of the passage, PE
Fluid 1 with minimal heat extraction from N4 overflow area 343
2 (arrow 12a) occurs. At the center of this region 343, virtually no current generating reaction occurs. Heat is supplied from the interconnector 4 to the region 343 via the comb-like protrusion 42 on the fluid 11 side.

The air side of the interconnector 4 can be configured to flow through a profiling with knob-like ridges 41 when the second fluid 12 (arrows 12 ', 12a) is supplied (see FIG. 1). (Fig. 6). The current generating reaction occurs in this supply region as well.

In a further exemplary embodiment with an interconnector 4 according to FIG. 8, the features of the supply passage 43 provided from the two embodiments according to FIGS. 6 and 7 are combined. Due to the knob-like ridge 41 of the passage 43, the PEN reaction supplying the current occurs here, albeit to a lesser extent, as well.

[0035]

According to the present invention, it is possible to further reduce costs in manufacturing a fuel cell.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a fuel cell cell according to the present invention.

FIG. 2 is a cross-sectional view of a specific cell and an adjacent second PEN.

FIG. 3 is a plan view showing a specific region of a normal basic form of a fuel cell battery.

FIG. 4 is a schematic diagram showing an interconnect having profiling viewed from the air side.

FIG. 5 is a schematic view showing the back surface of the interconnector of FIG. 4;

FIG. 6 is a cross-sectional view of a part of the cell stack.

FIG. 7 is a schematic view showing a modification of the interconnector of FIG. 4;

FIG. 8 is a sectional view of still another interconnector.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fuel cell battery, 2 ... Laminated body, 3 ... PEN, 4 ... Interconnector, 5 ... Common passage, 11 ... First fluid (fuel gas), 12 ... Second fluid (air), 24 ... Direction change Areas 41 profiling (knob-shaped ridges), 42 profiling (comb-shaped ridges).

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Emad Batavi CH-8400 Winter tool Steinberggasse 20 F-term (reference) 5H026 AA06 BB01 CC04 CC08 CV01 CV10 HH00 HH03 HH05

Claims (10)

[Claims] 1. A fuel cell (1) comprising a stack (2) of planar cells (3, 4), comprising: a) PEN as an electrochemically active plate (3) and an interconnector (4). B) the PEN and the interconnector each have a first edge (21) and a second edge (22), the first edge (21) and the second edge A straight or curved area (20) having a substantially constant width extending between the two areas (22); c) this area is divided into small sections (23) through which the two areas are divided; Edges (21,22) are connected; d) Interconnector is profiled (41,4)
2) allows the two fluids (11, 12) to flow separately through the cell; e) each sub-compartment has a first fluid (11) at a first margin (21). ), The inflow point (21) for the second fluid at the second margin (22).
2) and an outlet point (213) for both fluids (11, 12) is provided; f) said outlet point (213) is open in a common passage (5) of the whole cell stack (2). G) In the fuel cell (1) supplied with said second fluid (12) as a heat carrier medium for reaction heat released in the PEN during operation, the interconnector (4) is formed in one layer The profiling is such that both fluids always flow in contact with the PEN respectively, and that the first edge (21)
Is provided with a diverting area (24) for reversing the direction of flow of the second fluid (12) and the dimensions of the cell so as not to exceed undesired thermal stress values in the PEN during operation. And a fuel cell battery. 2. The fuel cell according to claim 1, wherein the individual interconnectors are preformed and sintered elements or are manufactured therefrom. 3. The profiling of the interconnector (4) has a knob-like ridge (41) providing an electrical contact to the PEN (3).
3. The fuel cell battery according to claim 1. 4. The profiling of the interconnector (4) for flowing the fluids (11, 12) has in particular a comb-like ridge (42) on the side of the second fluid (12), and these ridges are PEN The fuel cell according to any one of claims 1 to 3, wherein an electrical contact to (3) is provided. 5. The fuel cell according to claim 4, wherein at least a part of the comb-like protrusion has a helical shape or is formed in a straight line and is directed in a radial direction. battery. 6. Each of the small sections (23) has a turning area (2).
And a passage (43) directed to 4) is provided.
6. The cross-section of claim 1 having a greater depth along a direction perpendicular to the PEN (3) compared to the corresponding depth of the remaining profiling. Fuel cell battery. In operation of the battery (1), at least one third of the waste heat generated in the PEN reaction is radiated (6).
7. The fuel cell according to claim 1, wherein the cells are dimensioned such that they are released from the cell stack (2). 8. The cell is configured to be at least approximately symmetrical about a center, and is capable of supplying the first fluid (11) via a central passage extending in the axial direction, preferably this passage. A reformer for treating the first fluid (11) is provided, a common passage is provided as an outer burner chamber at the outlet point, and the stack (2) around the cell stack (2) is permeable. The fuel cell according to any one of claims 1 to 7, wherein the reaction fluid is absorbed when the second fluid flows into the cell. battery. 9. The sub-partitions (23) are equal in size,
9. The fuel cell battery according to claim 8, wherein the number is 4 to 10. 10. The use of a fuel cell according to claim 1 in a mobile application, as a current supply element in a motor vehicle or emergency power aggregate, as an example.